Researchers in southern Africa are racing to track the concerning rise of a new variant of the coronavirus that causes COVID-19.
The variant harbours a large number of mutations found in other strains, including Delta, and seems to be spreading quickly across South Africa.
It was first identified in Botswana this month and has turned up in travellers to Hong Kong from South Africa.
Scientists are also trying to understand the variant's properties, such as whether it can evade immune responses triggered by vaccines and whether it causes more or less severe disease than other variants do.
A World Health Organization expert group will meet on Friday and will likely label the strain as a variant of concern or variant of interest.
Travellers arriving in Britain from several southern African countries will have to quarantine amid warnings over the new COVID variant.
British Health Secretary Sajid Javid said, effective Friday, six countries would be added to the red list, with flights being temporarily banned.